Genomes carry millions of noncoding variants, and identifying the tiny fraction with functional consequences is a major challenge for genomics. We assessed the role of selection on long noncoding RNAs (lncRNAs) for domestication-related changes in rice grains. Among 3363 lncRNA transcripts identified in early developing panicles, 95% of those with differential expression (329 lncRNAs) between Oryza sativa ssp. japonica and wild rice were significantly down-regulated in the domestication event. Joint genome and transcriptome analyses reveal that directional selection on lncRNAs altered the expression of energy metabolism genes during domestication. Transgenic experiments and population analyses with three focal lncRNAs illustrate that selection on these loci led to increased starch content and grain weight. Together, our findings indicate that genome-wide selection for lncRNA down-regulation was an important mechanism for the emergence of rice domestication traits.
N6-methyladenosine (m6A) methylation functions as a vital post-transcriptional and epigenetic modification in higher plants regulated by α-ketoglutarate-dependent dioxygenases (ALKBH). However, the role of ALKBH genes in oriental melon (Cucumis melo L.) fruit ripening has not been explored. Therefore, we treated oriental melon with an exogenous m6A demethylase inhibitor (mechlorfenamic acid) then analyzed endogenous ethylene production and ripening-related indicators to explore the effects of m6A methylation on ripening. Bioinformatics and real-time quantitative PCR analyses were used to determine the impact of ALKBH genes on key ethylene synthesis gene expression. Treatment effectively inhibited endogenous ethylene production, firmness changes, and soluble solid contents, thereby extending fruit ripening. Eight ALKBH gene family members belonging to five major groups were identified in the melon genome. All members were expressed in ripening fruits, with different expression patterns during ripening. CmALKBH6, CmALKBH7, and CmALKBH8 expression was inhibited by an ethylene inhibitor (1-methylcyclopropene). The transient overexpression (OE) of CmALKBH8 in oriental melon led to the increased expression of the ethylene synthesis genes CmACS1, CmACS2, and CmACO1. In summary, the ethylene-regulated gene CmALKBH8 may participate in oriental melon fruit ripening regulation by modulating the methylation levels of ethylene synthesis-related genes. These findings help us better understand how m6A methylation regulates melon ripening.
12 October 2022 in Journal of Plant Growth Regulation